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A new hapalodectid (Mesonychia, Mammalia) from the Late Paleocene of the Qianshan Basin (Anhui Province, China): new data on the radiation of the hapalodectids
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Mesonychians are an extinct group of primitive hoofed mammals. They have been found all over Laurasia and were well diversified: more than 20 genera are presently recorded. Mesonychia are divided into two families: Hapalodectidae and Mesonychidae. Hapalodectidae are recorded from the late Paleocene to the middle Eocene in Asia (Gashatan to Irdinmanhan), and in the early Eocene in North America (from Wasatchian to early Bridgerian). Hapalodectids remained small: the species of Hapalodectes, the type genus of the family, weighed between 500 g and 1 kg. Because the hapalodectids are relatively rare mammals, the discovery of new specimens, especially in the Paleocene, is crucial for understanding the evolution of these peculiar mammals. Field work in Qianshan Basin (Anhui Province, China) led to the discovery of a new lower jaw of the mesonychian Hapalodectes in Gashatan (late Paleocene) sediments. It is worth noting that the fragmentary mandible is only the third specimen of Hapalodectidae discovered in the Paleocene, and the first in southeast China. The premolars and molars of the new fossil are morphologically similar to Hapalodectes dux, the most primitive hapalodectid, but their relative proportions recall H. paleocenus and the Eocene Hapalodectes species. As a result, the fossil described herein appears to be different from the other previously described species of Hapalodectes in being morphologically intermediate between H. dux and the other Hapalodectes species; it is thus identified as a new species. Its discovery is important because it sheds light on the initial radiation of the hapalodectids. The presence of the most primitive hapalodectids in Mongolia (e.g., H. dux) suggests that the Mongolian area is the center of origination of this carnivorous family. The differences between the new species and the Eocene hapalodectids from China, H. huanghaiensis and H. hetangensis, imply that these species do not derive from the newly described species. Therefore, the new Chinese hapalodectid allows reconstructing the existence of two dispersals from the Mongolian area to the southeast of China, before and shortly after the Paleocene–Eocene boundary. At that latter time, Hapalodectes also dispersed from Asia to North America; this event was part of the 'East of Eden' dispersals. The Paleocene/Eocene transition thus appears as a crucial event for the distribution and radiation of the hapalodectids with the establishment of two distinct groups, respectively in North America and in the southeast of China. Grant Information This abstract is a contribution to the Belgian Bilateral Cooperation Project Belspo BL/36/C54 and China International S&T Cooperation Project MOST 2009DFA32210.
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RBINS Staff Publications 2016
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A new hero emerges: another exceptional mammalian spine and its potential adaptive significance
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RBINS Staff Publications
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A new jewel-like species of the pill-millipede genus Sphaerobelum Verhoeff, 1924 (Diplopoda, Sphaerotheriida, Zephroniidae) from Thailand
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RBINS Staff Publications 2023 OA
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A new large species of the snake Palaeophis from the Lutetian marine margin of the Congo Basin, Cabinda, Angola
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Numerous fossil localities were investigated in western central Africa during the Belgian expeditions that started in the 19th century. At least 47 localities were excavated or analyzed in the framework of Edmond Dartevelle’s paleontological expeditions of 1933 and 1937-1938, producing a large and unique collection of Mesozoic-Cenozoic vetebrates from the margin of the Congo Basin along the coastal area of Angola to Gabon. Among them, snake vertebrae from the marine Paleocene-Eocene Landana section, Cabinda enclave, Angola have been referred to the aquatic snake Palaeophis aff. typhaeus. New investigation of the old Dartevelle’s collections has led to relocation of a few undescribed snake vertebrae from Landana and the nearby locality of Sassa Zao, permitting a revision of Palaeophis aff. typhaeus. The results of this work indicate that all specimens from Landana originate from the same stratigraphic level (layers 31-32) and are of Lutetian age based on the rich associated elasmobranch fauna. The locality of Sassa Zao is also Lutetian based on elasmobranchs that are similar to those of layer 32 of Landana. All of the vertebrae, ten in total, can be attributed to a single large species of Palaeophis. The maximum width across the prezygapophyses is 35 mm and the maximum length of the centrum is 27 mm. The weak lateral compression of trunk vertebrae, low development of the pterapophyses, diapophyses not very low, and the marked lateral projection of the zygapophyses indicate that this species belongs to the ‘primitive’ grade of Palaeophis and thus differs from species of the ‘advanced’ group such as P. casei, P. ferganicus, P. littoralis, P. toliapicus, P. typhaeus, P. grandis, P. tamdy, P. nessovi, and P. udovichenkoi. Among ‘primitive’ grade species, it differs from the giant P. colossaeus by smaller size, proportionally longer vertebrae, the cotyle and condyle more oval in shape, and the zygosphene not larger than the cotyle; from P. africanus by the neural spine that does not approach the zygosphene and shorter hypapophyses that are not prolonged by a ventral carina; from P. vastaniensis, P. virginianus, and P. zhylan by less depressed vertebrae. In size and morphology it most closely resembles P. maghrebianus but differs by more developed hypapophyses and paradiapophyses that do not extend over the cotyle posteriorly. This new species was apparently poorly adapted to aquatic life and was more closely related to the North African Ypresian P. maghrebianus than to West African Lutetian species. Grant Information This abstract is a contribution to the project BR/121/A3/PalEurAfrica funded by the Belgian Science Policy Office.
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RBINS Staff Publications 2016
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A new leaf-toed gecko (Gekkonidae: Dixonius ) from the city of Ranong, southwestern Thailand
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We describe Dixonius dulayaphitakorum sp. nov. from Ranong city, Ranong Province, southern peninsular Thailand. The new, ground-dwelling species differs from all currently recognized Dixonius by a combination of morphological characters and pattern: maximal known SVL of 47.8 mm, 22 longitudinal rows of dorsal tubercles; 33 to 35 paravertebral scales; 22 longitudinal rows of ventrals across the abdomen; six or seven precloacal pores in males, no pores in females; no distinct canthal stripe; and a spotted dorsal pattern. Based on dorsal pattern, the new species seems related to Dixonius siamensis. This description brings to 11 the number of Dixonius species, and to five the ones endemic to Thailand.
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RBINS Staff Publications 2020
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A new limestone-dwelling Four-clawed Gecko from Sa Kaeo Province, eastern Thailand (Squamata, Gekkonidae: Gehyra)
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We describe Gehyra shiva sp. nov. from limestone cave and hills in Khlong Hat District, Sa Kaeo Province, eastern Thailand, near the border with Cambodia. The new species differs from all currently recognized Southeast Asian Gehyra by the following combination of morphological characters and dorsal color pattern: maximal known snout–vent length of 53.8 mm, 8–10 supralabials, 54–67 dorsal and 46–56 ventral scale rows around midbody, absence of skin folds on limbs, 34–37 preanofemoral pores in males in a continuous series extending along the whole length of the femur (pores absent in females), tail not to moderately widened behind vent in adults, a single row of widened subcaudals, digits and toes unwebbed, 7 or 8 divided subdigital lamellae on 4th toe, and a dorsal pattern with five regular dark brown bands between limb insertions, separated or not by pairs of large, white round paravertebral spots.
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RBINS Staff Publications 2025
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A new lithostratigraphy for the Quaternary sandy aeolian deposits in Belgium: revising the Gent formation
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RBINS Staff Publications 2017
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A new longirostrine beaked whale Flandriacetus gijseni gen. et sp. nov. (Ziphiidae, Cetacea, Mammalia) from the Tortonian of the North Sea Basin
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RBINS Staff Publications 2025
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A New Mammal Skull from the Late Cretaceous of Romania and Phylogenetic Affinities of Kogaionid Multituberculates
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Among the Late Cretaceous fossil sites of Europe, only those from the so-called “Haţeg Island” in Transylvania, western Romania, are remarkable by their abundance in mammal remains. Curiously, all of them belong to a single family of multituberculates, the Kogaionidae, one of the rare families that survived the Cretaceous-Paleogene mass extinction in Europe. Kogaionids are mostly represented by isolated teeth except for three partial large skulls from the Maastrichtian Sânpetru Formation of the Haţeg Basin that have been described from the Sânpetru locality as Kogaionon ungureanui and from the Pui locality as Barbatodon transylvanicus and Litovoi tholocephalos. Here we report for the first time the discovery of a partial skull associated with p4 of a small-sized kogaionid from the Nălaţ-Vad locality in the Sânpetru Formation that we refer to Kogaionon radulescui, sp. nov. An updated phylogenetic analysis, including seven Maastrichtian and Paleocene kogaionids is performed and confirms that Kogaionidae is a monophyletic clade at the base of Cimolodonta. Kogaionon differs from Barbatodon in its narrower snout, proportionally smaller P1, narrower anterior part of P4 with four similar-sized cusps in the middle row, more squared or rounded M1 with an anteroposteriorly longer lingual row, and shorter p4 (at least for K. radulescui). Litovoi tholocephalos is here considered to be a junior synonym of B. transylvanicus. Despite their Maastrichtian age, the very simple and conservative dental morphology of these Romanian kogaionids suggests that they originated from an eobaatarid-like ancestor dispersing from Asia or possibly already existing in Europe between the Barremian and Albian, 40 to 55 Ma earlier.
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RBINS Staff Publications 2021
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A new Palaearctic Amblypsilipus Species (Insecta, Diptera, Dolichopodidae) from Turkey
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